Complex number (1 Viewer)

[juantheron]

 

[deterministic]

See that where r is the modulus and is the argument. Your aim is then to find the theta and r.

r is obvious to find.

Consider . We know that the sides z1, z2, z1-z2 forms a triangle with side lengths 3,4 and respectively (draw a diagram to convince yourself). We know that the argument of is just the angle between z1 and z2 (arg(z_1)-arg(z_2)). This is just the angle opposite to vector z1-z2. Use cos rule to find . Then you should be done.